ORAC values: Measuring the antioxidant power of foods

If you spend a lot of time reading about nutrition, you probably feel as if we’re all in a contest to see who can eat the most antioxidants. Those who are interested in (obsessed with?) antioxidant nutrition will often talk about a food’s ORAC value. As in, “Wild blueberries have an ORAC value of 9,621, while regular blueberries only have an ORAC of 4,669!” What on earth are these people talking about? NMTBP investigates

The term ORAC stands for Oxygen Radical Absorbance Capacity, a method used to measure the antioxidant capacity of different foods and substances. Antioxidants are crucial in neutralising free radicals and unstable molecules that can damage cells and contribute to ageing, cancer, and other diseases. Understanding ORAC values can help individuals make informed choices about which foods are the richest in antioxidants, potentially aiding in better health and disease prevention

The nice thing about this method is that it measures the antioxidant activity of food rather than the levels of specific nutrients, such as vitamin C or E. After all, there are thousands of unique antioxidant compounds in plants, most of which we haven’t even discovered yet. There’s no way we could measure them all individually. This approach would also capture any synergistic effects between the various nutrients – ways in which nutrients are more effective in combination than they are individually

What Are ORAC values?

ORAC values are a scientific measure used to quantify the antioxidant strength of foods and supplements. The higher the ORAC score, the stronger the food’s potential to fight oxidative stress by neutralising free radicals. Oxidative stress refers to an imbalance between free radicals and antioxidants in the body, leading to cell damage and contributing to various health issues, including inflammation, heart disease, and cancer

The ORAC test was developed by the National Institute on Aging (NIA) at the National Institutes of Health (NIH). It evaluates a substance’s ability to protect molecules from oxidation caused by free radicals. By comparing the antioxidant capacities of various foods, researchers aim to determine which ones provide the most protection against oxidative damage

How ORAC values are measured

In an ORAC test, a food sample is placed in a solution and exposed to a source of free radicals. The antioxidants present in the sample then neutralise these radicals. The ORAC value is calculated based on the sample’s ability to absorb and neutralise a certain number of free radicals. The results are expressed in micromoles of Trolox equivalents (µmol TE) per 100 grams. Trolox is a water-soluble analogue of Vitamin E used as a benchmark for antioxidant capacity

While ORAC values provide a standardised way to measure antioxidant capacity, it is essential to understand that a high ORAC score does not necessarily mean a food will have the same effect inside the human body. Bioavailability (how well the body absorbs and uses a nutrient) varies between foods, and factors such as food preparation, digestion, and individual health can impact the efficacy of these antioxidants

Where to Find ORAC Values

The lab that developed one of these tests has measured the ORAC values in hundreds of foods and spices and published those values in a database, which you can find online. Some of the results might surprise you. For example, who would have thought that whole-grain bread has a higher antioxidant capacity than bean sprouts? Or that kidney beans pack four times the antioxidant punch of broccoli?

Some of the results are misleading. For example, you’ll find spices like cinnamon and cloves with 6-digit ORAC values. However, all of the ORAC scores refer to 100-gram servings. Once you convert these into the amounts you’d typically consume in a meal, cinnamon and cloves are comparable to the antioxidant activity of small apple or pear

Once this database was published, it was inevitable that people (as well as marketers) would start competing to see who could rack up the highest score

Health benefits of foods with high ORAC values

Incorporating foods with high ORAC values into your diet may help protect against oxidative stress and reduce the risk of chronic diseases. Some potential benefits include:

Cardiovascular health: Antioxidants can help reduce inflammation and prevent damage to blood vessels, lowering the risk of heart disease
Cognitive function: Certain antioxidants, such as those found in berries, have been linked to improved brain health and a lower risk of neurodegenerative diseases like Alzheimer’s
Cancer prevention: Antioxidants are believed to protect DNA from damage, which may reduce the risk of mutations leading to cancer
Skin health: The antioxidants in foods like berries and dark chocolate can help protect skin cells from UV damage and reduce signs of ageing

Limitations and Criticism of ORAC Values

While ORAC values provide insight into the antioxidant potential of foods, they are not without limitations. Some of the primary criticisms include:

Bioavailability: ORAC values measure the potential antioxidant activity of a food in a test tube, not in the human body. Not all antioxidants are equally absorbed, and some may not even reach the bloodstream in significant amounts
Overemphasis on ORAC numbers: Focusing solely on high-ORAC foods can be misleading. A well-rounded diet, rich in various fruits and vegetables, is more important than relying on just a few “superfoods”
Outdated measure: The USDA discontinued publishing ORAC values in 2012, stating that the methodology does not directly correlate to health benefits. Since then, many nutrition experts have suggested focusing on whole foods and dietary patterns rather than specific ORAC scores
Synergy of nutrients: Antioxidants often work better in combination with other nutrients rather than in isolation. The effects seen in lab studies may not replicate in real-world settings

Antioxidants are just one aspect of nutrition

ORAC values are a valuable tool for comparing the antioxidant potential of different foods. However, they should not be the sole factor when making dietary choices. Eating various antioxidant-rich foods like fruits, vegetables, nuts, and spices can help promote overall health and reduce disease risk. It’s important to focus on a balanced diet, rich in whole foods, rather than becoming fixated on specific ORAC numbers.No superfruits or supplements required!